Downhole apparatus and method

Abstract

A downhole tool (32) comprises a tool housing (34) defining a central bore (35) and including a fluid port (20), and a valve member (40) mounted within the housing (34) and being moveable from a closed position in which the fluid port (20) is blocked to an open position in which the fluid port (20) is opened. The tool (32) further comprises a catching arrangement (41) mounted within the housing (34) and comprising one or more radially moveable seat members (106), and being configurable from a free configuration in which the seat members (106) permit an object (48) to pass through the tool (32), to a catching configuration in which the seat members (106) catch an object (48) passing through the tool (32).

The invention claimed is: 
     
       1. A downhole tool, comprising:
 a housing; 
 a catching arrangement mounted within the housing and comprising one or more radially moveable seat members, and being configurable from a free configuration in which the seat members permit an object to pass through the tool, to a catching configuration in which the seat members catch an object passing through the tool; and 
 a release member comprising an axially moveable sleeve mounted within the housing and being moveable axially by the catching arrangement between a supporting position in which the release member permits the catching arrangement to be configured in its catching configuration by the release member radially supporting the seat members in a radially inward or retracted position, towards a de-supporting position in which the release member permits the catching arrangement to be configured in a release configuration by removing the radial support to the seat members provided by the release member, allowing the seat members to be moved radially outwardly to permit release of a previously caught object. 
 
     
     
       2. The downhole tool according to  claim 1 , wherein the housing defines a release recess and the release member covers this release recess when said release member is located within its supporting position, and the release member is movable within the housing towards its de-supporting position to uncover the release recess and thus permit the seat members to be moved radially outwardly and received within the release recess to permit release of an object. 
     
     
       3. The downhole tool according to  claim 1 , wherein the release member defines a load profile, and the catching arrangement defines a load profile configured to engage a load profile on the release member to permit the catching arrangement to apply a force on the release member to move the release member towards its de-supporting position. 
     
     
       4. The downhole tool according to  claim 1 , wherein at least one seat member comprises a load profile configured to engage a load profile on the release member to permit the release member to be moved by the catching arrangement. 
     
     
       5. The downhole tool according to  claim 1 , wherein each seat member comprises a load profile, wherein when said seat members are moved radially inwardly the individual load profiles define a substantially circumferentially continuous load profile. 
     
     
       6. The downhole tool according to  claim 1 , wherein the catching arrangement is biased in a direction opposite to the direction in which the release member is moved to be positioned within its de-supporting position. 
     
     
       7. The downhole tool according to  claim 1 , wherein the housing defines a central bore and includes a fluid port, and the downhole tool further comprises a valve member mounted within the housing and being moveable from a closed position in which the fluid port is blocked to an open position in which the fluid port is opened. 
     
     
       8. The downhole tool according to  claim 7 , wherein the catching arrangement is reconfigured by movement of the valve member towards its open position. 
     
     
       9. The downhole tool according to  claim 7 , wherein the catching arrangement is configured to catch an object passing through the tool to at least partially block flow through the central bore and divert flow through the fluid port when opened. 
     
     
       10. The downhole tool according to  claim 7 , wherein the valve member is moveable from its closed position towards its open position in response to an object passing through the downhole tool in a downstream direction. 
     
     
       11. The downhole tool according to  claim 10 , wherein the catching arrangement catches the same object which causes movement of the valve member towards its open position. 
     
     
       12. The downhole tool according to  claim 7 , wherein the valve member is axially moveable by an indexing sleeve of a downhole actuator. 
     
     
       13. The downhole tool according to  claim 12 , wherein the indexing sleeve is located on an upstream side of the valve member, and functions to move the valve member in a downstream direction. 
     
     
       14. The downhole tool according to  claim 12 , wherein the indexing sleeve is operated to move linearly through the housing in a predetermined number of discrete movement steps to actuate the valve member by passage of a corresponding number of objects. 
     
     
       15. The downhole tool according to  claim 14 , wherein a final discrete movement step of the indexing sleeve initiates movement of the valve member towards its open position. 
     
     
       16. The downhole tool according to  claim 15 , wherein the catching arrangement catches an object which caused the final discrete movement step of the indexing sleeve. 
     
     
       17. The downhole tool according to  claim 7 , wherein the valve member is arranged to axially engage the catching arrangement to move the catching arrangement within the housing, wherein the valve member and catching arrangement comprise respective load profiles which are arranged to abut each other in an axial direction. 
     
     
       18. The downhole tool according to  claim 7 , comprising a lost motion arrangement between the valve member and the catching arrangement to permit the valve member to move a desired distance relative to the catching arrangement before initiating axial movement of the catching arrangement. 
     
     
       19. The downhole tool according to  claim 7 , wherein the valve member comprises an axially extending shroud which extends into the catching arrangement from one axial end thereof such that an end region of the catching arrangement sits radially outside of the valve member shroud and isolated from the central bore. 
     
     
       20. The downhole tool according to  claim 19 , wherein the shroud extends only partially through the catching arrangement. 
     
     
       21. The downhole tool according to  19 , wherein the shroud extends into the catching arrangement at least when the catching arrangement is configured in its free configuration. 
     
     
       22. The downhole tool according to  claim 1 , wherein the downhole tool defines a first region within the housing having a first inner diameter which permits the seat members to move radially outwardly when aligned with said first region, and the catching arrangement is provided in its free configuration when the seat members are aligned with the first region. 
     
     
       23. The downhole tool according to  claim 22 , wherein the downhole tool defines a second region within the housing having a second inner diameter which permits the seat members to be radially supported when positioned radially inwardly, when aligned with said second region, and the catching arrangement is provided in its catching configuration when the seat members are aligned with the second region. 
     
     
       24. The downhole tool according to  claim 23 , wherein the catching arrangement is axially moveable within the housing to realign the seat members from the first region to the second region, and thus present the catching arrangement in its catching configuration. 
     
     
       25. The downhole tool according to  claim 1 , wherein the seat members collectively define a substantially complete annular structure when positioned radially inwardly. 
     
     
       26. The downhole tool according to  claim 1 , wherein the catching arrangement comprises a tubular portion and a plurality of collet fingers supported by the tubular portion, wherein each collet finger supports a respective seat member. 
     
     
       27. The downhole tool according to  claim 26 , wherein each collet finger is radially deformable to permit the respective seat members to be moved radially outwardly and inwardly. 
     
     
       28. The downhole tool according to  claim 26 , wherein at least one collet finger defines a tapering radial width. 
     
     
       29. The downhole tool according to  claim 1 , comprising a lost motion arrangement between the catching arrangement and the release member to permit the catching arrangement to move a desired distance relative to the release member before initiating axial movement of the release member towards its de-supporting position. 
     
     
       30. A method for catching and releasing an object in a wellbore using a downhole tool, comprising:
 configuring a catching arrangement which is located within a housing in a free configuration such that one or more radially moveable seat members of the catching arrangement permit an object to pass through the tool; 
 reconfiguring the catching arrangement in a catching configuration in which the seat members catch an object passing through the tool; and 
 axially moving a release member comprising a sleeve using the catching arrangement between a supporting position in which the release member permits the catching arrangement to be configured in its catching configuration by the release member radially supporting the seat members in a radially inward or retracted position, towards a de-supporting position in which the release member permits the catching arrangement to be configured in a release configuration by removing the radial support to the seat members provided by the release member, allowing the seat members to be moved radially outwardly to permit release of the caught object. 
 
     
     
       31. A downhole tool, comprising:
 a housing; 
 a catching arrangement mounted within the housing and comprising one or more radially moveable seat members, and being configurable from a free configuration in which the seat members permit an object to pass through the tool, to a catching configuration in which the seat members catch an object passing through the tool; and 
 a release member mounted within the housing and being moveable axially by the catching arrangement between a supporting position in which the release member permits the catching arrangement to be configured in its catching configuration by radially supporting the seat members in a radially inward or retracted position, towards a de-supporting position in which the release member permits the catching arrangement to be configured in a release configuration by removing the radial support to the seat members, allowing the seat members to be moved radially outwardly to permit release of a previously caught object, 
 wherein the release member defines a load profile, and the catching arrangement defines a load profile configured to engage a load profile on the release member to permit the catching arrangement to apply a force on the release member to move the release member towards its de-supporting position. 
 
     
     
       32. The downhole tool according to  claim 31 , wherein at least one seat member of the catching arrangement defines a portion of the load profile of the catching arrangement. 
     
     
       33. A downhole tool, comprising:
 a tool housing defining a central bore and including a fluid port; 
 a valve member mounted within the housing and being moveable from a closed position in which the fluid port is blocked to an open position in which the fluid port is opened; 
 a catching arrangement mounted within the housing and comprising one or more radially moveable seat members, and being configurable from a free configuration in which the seat members permit an object to pass through the tool, to a catching configuration in which the seat members catch an object passing through the tool; and 
 a lost motion arrangement between the valve member and the catching arrangement to permit the valve member to move a desired distance relative to the catching arrangement before initiating axial movement of the catching arrangement. 
 
     
     
       34. The downhole tool according to  claim 33 , comprising a release member mounted within the housing and being moveable axially by the catching arrangement between a supporting position in which the release member permits the catching arrangement to be configured in its catching configuration by radially supporting the seat members in a radially inward or retracted position, towards a de-supporting position in which the release member permits the catching arrangement to be configured in a release configuration by removing the radial support to the seat members, allowing the seat members to be moved radially outwardly to permit release of a previously caught object. 
     
     
       35. A downhole tool, comprising:
 a housing; 
 a catching arrangement mounted within the housing and comprising one or more radially moveable seat members, and being configurable from a free configuration in which the seat members permit an object to pass through the tool, to a catching configuration in which the seat members catch an object passing through the tool; 
 a release member mounted within the housing and being moveable axially by the catching arrangement between a supporting position in which the release member permits the catching arrangement to be configured in its catching configuration by the release member radially supporting the seat members in a radially inward or retracted position, towards a de-supporting position in which the release member permits the catching arrangement to be configured in a release configuration by removing the radial support to the seat members provided by the release member, allowing the seat members to be moved radially outwardly to permit release of a previously caught object; and 
 a lost motion arrangement between the catching arrangement and the release member to permit the catching arrangement to move a desired distance relative to the release member before initiating axial movement of the release member towards its de-supporting position.